Process of tanning hides or other animal tissues.



To all whom it may concern:

, UNITED STA -si'iPATENT OFFICE.

o'r'ro P. AMEND, on NEW YORK, N. Y.

PROCESS OF TANNING HiDES OR OTHER ANIMAL TISSUES.

sflscmcsnon forming part of 1mm Patent No. 713,046, dated. November 1 1, 1 902.

Y Application filed April 18. 1902. Serial No. 103,580. (No specimens.)

Be it known that I, O'rro P. AMEND, a citizen of the United States, residing in the city, county, and State of New York, have invented a certain new and useful Process for the Tanning of Hides or Other Animal Tissues, of which the following is a specification;

The history of the art of tanning is so well .known by those skilled in its application that it is unnecessary to give the details thereof. It may be stated in a general way, however,

that at the present time practically only two methods of tanning are employed. One of these is'the well-known process in which organic extracts containing tannin are used and the other is'that known as mineral tan- 1 uage. It is to the latter that my invention relates.

The methods of tanning by meahs of metallic salts such as the salts of chromium and iron, forinstance-have been known for many years; but such processes are more or less complicated and require a skilled chemistin order to produce good results, while the neceuary step of puring in addition to weakening the structure of the skin also requires constant care and attention to prevent destrnction of the skin by -climatic changes, such as rises in temperature and electrical disturbances. The leather prod need by these ployed processes leaves much to be desired in regard to quality, and the time required for the tanning operation is very considerable.

-I have discovered that many of the defects inherent in tanning by means of mineral -salts are obviated -by thc employment of a tanning liquor or solution which contains a nitrate of a lc:|.ther-forming metal and that the time required-for the tanning of a skin or .hide is very materially.shortened. ".lh us leather tanned in my solutions is superior to that produced by other known metallic processesfin that it has a more porou's or open toxture; owing to less-contraction during tannagt and this facilitates the washing out or firming by any well-known means of any acid which it-may contain, while the grain is left in a much better condition for subsequent mani nlation or treatment than when produce by the other-processes at present om- Again, I have found that the time for tanning a hide is so much shortened by" using my solutions that an ordinary sheep, goat, or calfskin, which requires immersion from sixteen to eighteen hours in a solution of a basic metallic salt, snch'as a basic sul-ff.

mersion of, say, twenty-four hours. Still, I

again, by using my solutionsthe operationof puring may be entirely dispensed with, and degreasiug is so far rendered unnecessary that ahi'de just as it is taken from the animalafter being fleshed and washed may be efiectively tanned in my solutions. 7

If depilati u is not desired, liming and bat-' ing are also dispensed with and theskin can be thoroughly tanned with the hairiinplace, while if the hair is to be removed liming and bating may be performed either before or after the skin has been tanned in my solutions.

If the skin is to be depilated, and consequentlylimed, I prefer to remove the lime chemically by washing in a weak solution of an acid, such as muriatic or acetic acid.

In preparing my solutions of a nitrite-of a leather-forming metal I dissolve a salt of one of the leather-forming mctals-ehromiuu1,

iron, aluminium-inwater at ordinary temperatures and also dissolveasoluble nitrite of an alkali metal such as nitrite of sodium, nitrite of potassium,'&c.or of an alkaline earth, such as nitrite of barium, in water at ordinary temperatures and then mix the two solutions to form my tanning solutions; In some cases there will be an insoluble precipitate formed together with a solution of a nitrite of the leather-forming metal contained' in the metallic salt, while inother cases no precipitate will be formed; but a partial decomposition takes place with the formation of h. nitrite of the leather-forming metal in the. In the former instance the precipi= solution. tat'e may be removed by filtration or decanta- 'tion, as is well understood,while in both cases it-is the solution containing the nitrite of-the mo leather-forming metal that furnishes the tanning agent. 7

As illustrations oi? the first elassof solutions, 1 dissolve seven hundred and seventeen (the molecular weight) grams of crystalline chr mic sulfate, Gr,(SO,),-| -18(H,O),- in about seven thousand grams of water'at ordinary temperatures. Ialso dissolve six hundred and eighty-seven (three times the molecular j weight) grams of barium-nitrite, Ba(NO,),, in about seven thousand grams of water at or- -dinary temperatures. I then mix the two solutions and remove the insoluble precipitate.

to ,The clear solution will contain nitrite of chro- ,mium and is the tanning liquor to be used. Agaiu, I dissolve three hundred and seventy-.-

1 four (the molecular weight) grams of chromic V oxalate, Cr (C,O,),, in about four thousand grams of water at ordinary temperatures. I also dissolve three hundred and sixty-nine f (three times the molecular weight) grams of 1 calcium nitrite, Ca(NO,),,'in about four thousand grams of water. I then mix the two soso lutions and remove the precipitate. The clear solution will contain nitrite of chromium and is the tanning liquor to be used. Of course the salts may be mechanically mixed first and then dissolved in water. I have found four :5 ounces of chromium nitrite to every gallon of water tobe an elficient and cheap tanning solution. When, however, the chlorids, acetates, formates, or nitrates of the metals are used with the nitrite of an alkali metal or of 3c an'alkaline earth, no precipitate may be forined, but a partial decomposition takes place, forming a metallic nitrite in the solution.

I have also found by experiment thatIcan 5 form an eflicient and cheap tanning solution by the use of chrome-alum,

as follows: I dissolve chrome-alum in, say, 40 ten parts of water'at ordinary temperatures and add to this solution a solution ofjsodium nitrite, Na(NO in, say, ten-parts of water at ordinary temperatures, the proportion of 'chromealum tosodium nitrite being one 5 molecule of the former to six molecules. of the latter. A mixture of the two solutions in the proportions of one part of the former to one-half part of the latter will form the tanning solution. 'There will be no precipi- 5 mm formed in this solution, but there will be a decomposition with the formation of nitrite of chromium in the solution. v A

Although I have specified chromium as the leather-forming metal in all of the foregoing examples and prefer to use it, I do not confine myself-tothe use of the salts of this metal; but my invention includes the use of the salts of the other leather-forming metals irou and aluminium, and the same proportions and 6c formulas as those above given for the use of ohromium will be eflioient with iron and aluminium, of con rse observing thedlfierence in molecular weight; nor do I confine myself to the use of the specific nitrites of the alkali metals named, but include theuse'of. any .soluble nitriteof an alkali metal or of analkaline earth. Neither do I confine myself to because it is obvious that the proportions of water may be varied according to the charstated proportions in'the illustrative examples are eflicient for a rapid tanning of an ordinary sheepskin, while a slower tanning may be eflected with a weaker solution.

steers, a stronger solution may be used, and tanning may be effected in eighteen to twenty hours. I may state that I have used efiectthe two salts each dissolved in seven parts of water, and, on the other hand, a mixed solution of the two salts each dissolved in ninety-nine parts of water. 1 From this it will he used directly for" tanning purposes or as stock solutions' which may be diluted with 'ning liquor desired.

In practicing my invention with chromechrome-alum one-half a pound of nitrite of sodium and dissolve the salts inwater in proportions of from one part of the mixed salts to eight parts of water up to one part of the I then immerse in this solution the undepi lated skin or pelt which has beenpreviously washed and fleshed, but which has not been pured. (Of course it can be pured, if desired.) The effeotiveness'of the .tanning in chrometanpage may be determined by the ordinary test of cutting-off a piece of a skin in the bath ,and immersing it in boiling water.

skin does not shrink, it has been converted into'leather. So,also,the'other ordinary tests are applied in the case of the other metals.

If depilation is desired, the skin may 'be limed, depilated, and hated beforeimmers ing it in the tanning-bath, or it may be limed, depilated, and bated after being tanned. If the skinis bated, I prefer. chemical hating by dissolving the lime in a weak solution of an acid, such-as muriatic or acetic acid.

The same process and corresponding stoi chiometrical proportions of salts should be used with the other salts of the different leather-forming metals and the nitrites of the alkali metals or of the alkaline earths, so as to forma nitrite of the'leather-forming metal.

Thus for tanning with chromic sulfate and barium nitrite I take for every one pound of chromic sulfate one pound of barium nitrite and dissolve the salts in water in proportions ofifrom one part of the mixed salts to eight parts of water up to one part of the mixed salts .to eighty parts of water, according to the strength of the solution desired, and so on for the other salts of the different leather-forming metals. 1

Of course my invention contemplates and comprises all methods of introducing into the actor of the hides to be tanned and the con-' sequent strength of the liquor desired. Thethe proportions of water specifically given, 1

Again, with heavier skins, such as those of' ively, on the one hand, a mixed solution of be understood that the original solutions may water according to the strength of the tanalum, for instance,-I take for every pound of mixed salts to eighty parts of water, accord ing to the strength of the solution desired.

If the bath or generating within the bath a nitrit-o 1' of a Mather-forming metal. I I do not inthe present appiioanion claim the solutions which form a pa 't of my pres-- ent invention, as such claims eonstitute Lha' subject-matter of A divisional appiicntion for: Letters Patent fiied January 25, 1901, Serial NO. 44,704,

1. The'process of tanning which consists in exposing the skin or hide to the action. of a, nitrite of a. tanning metal in solution.

chromium nitrite in solution.

OTTO P. AMEND.

\Vianessesi JAMES M. STEWART,

vHaving thus described my invention, What JACOB 13, T0011.

I claim is- It hereby certified that in Lettera Patent No. 713,046 granted November 11, 1902, np0n tile APPHUHXZEOII of Otto I". Amend, of New YorkQNQY. for an improvement in Processes of Tanning Hides 01 other Animal" Tissues an error a pezu-s in the printed specifiuition iw' uii-ing correction, as foiiows: In line page 1 the word nitraio should read waif "29ml that the said Letters Pat enfi siionid be read with this correction therein Pat ent Oflice Signed and sealed thii that: the same may conform to the record of the case in the [SEAL.]

2. The process of banning which consists in, exposing the skin or hide to the action of 1'5 It is hereby certified that in Letters Patent No. 713,046, granted November 11, 1902, upon the applicntioo of Otto I. Amend, of New YorkLN. Y., for an improvement in Processes of Tanning Hides or other Animal Tissues, an error appears in the printed specifimtion requiring correction, as follows: In line 39, page 1, the. word nitrate should teal] witr'z'la; :flml that thosaid Letters Patent sllould be rczid with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 25th day of November, A. ll, 1&102.

F. I. ALLEN,

Commissionr of Patents.

[SEAL] 

